Early Middle Ages

The Abbasid Caliphate

The Abbasid Caliphate (750–1258): the golden age of Islamic civilization, the House of Wisdom, philosophy and science, and the slow political fragmentation.

In-depth article

The Abbasid caliphate (750-1258) was the second of the two great dynastic polities of the Islamic world and the one that, in many ways, defined the classical civilization of Islam. Founded by the Abbasid revolution that overthrew the Umayyad caliphate, the dynasty presided over an empire whose capital, Baghdad, became, for several centuries, the political and intellectual capital of the world. The early Abbasid period, in particular the reigns of al-Mansur, Harun al-Rashid, and al-Ma’mun, was the golden age of Islamic civilization: the era of the great translations of Greek, Persian, Indian, and Syriac learning into Arabic; of al-Khwarizmi and the foundations of algebra; of al-Kindi and the foundations of Islamic philosophy; of the four great schools of Sunni law; and of the synthesis of Sufi mysticism. The political fortunes of the Abbasid caliphate did not long survive its first flowering, and the dynasty was, from the mid-ninth century onward, increasingly the prisoner of its own soldiery and the hostage of regional powers. But the institution itself, recognized by much of the Sunni Muslim world as the legitimate caliphate, endured in Baghdad until its destruction by the Mongol conquest of 1258.

The Abbasid period was, in short, the formative era of classical Islamic civilization. The institutions of the law, the theological traditions, the philosophical and scientific syntheses, the literary canons of the Arabic language, and the architectural and artistic traditions of the high medieval Islamic world all took shape, in their mature form, in the Abbasid period. The translations and original works produced in Baghdad in the ninth and tenth centuries were, alongside the Sanskrit, Syriac, and Pahlavi works on which they drew, among the most important intellectual achievements of the early medieval world. They would, in the following centuries, form the principal bridge by which the heritage of Greek thought, Indian mathematics, and Persian statecraft was transmitted to the Latin West.

The Abbasid Revolution

The Abbasid revolution of 749-750 was a long time in the making. The Abbasid movement, which claimed descent from the Prophet’s uncle Abbas ibn Abd al-Muttalib, took shape in the second half of the eighth century, drawing on the Shia sense of grievance against the Umayyads, the resentment of the mawali (non-Arab Muslim converts), and the support of the Iranian and Central Asian populations incorporated into the caliphate. The Abbasid agents, working in the eastern province of Khurasan, organized a long underground campaign, and in 749, as the last Umayyad caliph Marwan II was distracted by other conflicts, raised a revolt.

The decisive event was the Battle of the Zab, fought in January 750 on the Greater Zab River in northern Mesopotamia, in which the Abbasid forces defeated Marwan II. The last Umayyad caliph fled to Egypt, where he was killed. A surviving Umayyad prince, Abd al-Rahman ibn Muawiyah, fled westward and eventually to al-Andalus, where he founded an independent Umayyad emirate that would become the caliphate of Cordoba. The Abbasid revolution was, in effect, a transfer of power from the Arab tribal aristocracy of the caliphate to a more cosmopolitan, Persianate ruling class.

The Early Abbasid Caliphs

The first Abbasid caliph, al-Saffah (r. 749-754), spent most of his short reign consolidating his position. The second, al-Mansur (r. 754-775), the true founder of the dynasty, founded the new capital of Baghdad in 762, on the Tigris River near the old Sasanian capital of Ctesiphon. Baghdad was laid out as a round city, with the caliphal palace at the center, and it was designed from the start as a great administrative and commercial capital, the new heart of the caliphate. Al-Mansur also suppressed the various revolts that had broken out in the early years of the dynasty, including a serious Shia revolt led by Muhammad al-Nafs al-Zakiyya, and consolidated Abbasid control over the central lands of the caliphate.

Al-Mahdi (r. 775-785) and al-Hadi (r. 785-786) continued the consolidation. The most famous of the early Abbasid caliphs is Harun al-Rashid (r. 786-809), who presided over the apogee of the dynasty and whose court at Baghdad was, in the eyes of contemporaries, the political and cultural capital of the world. The “Thousand and One Nights” preserves a vivid, if romanticized, picture of his court. Harun conducted major wars against the Byzantine Empire and maintained the elaborate court ceremonial established by his predecessors. His son al-Amin (r. 809-813) was defeated in a civil war by his brother al-Ma’mun (r. 813-833), who presided over the high point of Abbasid cultural patronage, including the foundation of the House of Wisdom in Baghdad.

The Abbasid Golden Age

The Abbasid golden age of the ninth and tenth centuries was a period of extraordinary cultural achievement. The translation movement, in which the great works of Greek, Persian, Indian, and Syriac scholarship were translated into Arabic, was one of the most important intellectual events of the medieval world. The major Greek works of philosophy, medicine, mathematics, and astronomy were translated, often through Syriac intermediaries, by scholars such as Hunayn ibn Ishaq, Thabit ibn Qurra, and al-Kindi. The Indian mathematical and astronomical tradition was transmitted through the embassy to the court of Harun al-Rashid and the work of scholars such as al-Khwarizmi, whose book on algebra gave the discipline its name and whose work on Hindu numerals provided the basis for the “Arabic” numerals that would, in later centuries, transform the mathematics of the Latin West.

The great syntheses of Islamic scholarship of the Abbasid period include the works of the philosopher al-Kindi (d. c. 866), the synthesizer of Greek philosophy and Islamic theology; the mathematician and astronomer al-Khwarizmi (d. c. 850), whose Algebra was a founding text of the discipline; the physician al-Razi (d. 925), author of the great medical encyclopedia; the philosopher al-Farabi (d. 950), whose works on the philosophy of Aristotle and Plato were foundational for Islamic philosophy; and the great synthesizer Ibn Sina (Avicenna, d. 1037), whose Canon of Medicine and Book of Healing would dominate the medical and philosophical traditions of both the Islamic world and the Latin West for centuries.

The religious sciences of Islam also took their mature form in the Abbasid period. The great collections of hadith - the Sahih of al-Bukhari and the Sahih of Muslim - were compiled in the ninth century, and the four great schools of Sunni law (the Hanafi, Maliki, Shafi’i, and Hanbali) all reached their mature form in the early tenth century. The great syntheses of speculative theology (Kalam) were produced in the same period, including the works of al-Ash’ari (d. 936) and al-Maturidi (d. 944). The Sufi tradition, which had begun in the eighth century, flowered in the ninth and tenth centuries, with figures such as al-Hallaj, Bayazid al-Bistami, and the great woman saint Rabi’a al-Adawiyya.

Political Decline

The political fortunes of the Abbasid caliphate did not long survive its cultural apogee. The caliphs had come to power with the support of the Khurasani Persian and Central Asian troops, but from the time of al-Mu’tasim (r. 833-842), the caliphs began to rely on Turkish slave soldiers (ghilman or mamluks) for their military support. The Turkish soldiers were a constant threat to the caliphs themselves, and from the mid-ninth century onward, the caliphs were, in effect, the prisoners of their own army. The Turkish commander-in-chief, the amir al-umara, was, by the 940s, the real power in Baghdad.

The caliphs also lost control of the provinces. The Aghlabids of Tunisia, the Tahirids and Samanids of Khurasan, the Buyids of western Iran, the Hamdanids of Syria, and the Fatimids of Egypt, North Africa, and eventually Syria all established independent or semi-independent rule. The Fatimid caliphate, which claimed descent from the Prophet’s daughter Fatima, was the most serious Abbasid rival, and at its height controlled Egypt, North Africa, and parts of Syria and the Hejaz. The Buyids, a Shia Iranian dynasty, took Baghdad in 945 and reduced the Abbasid caliphs to figureheads. The Buyids were in turn displaced by the Seljuk Turks, who took Baghdad in 1055 and established a Sunni revival.

The Late Abbasid Caliphate

The late Abbasid caliphate, from the eleventh century to the thirteenth, was a shadow of its former self. The caliphs of Baghdad, restored to nominal sovereignty by the Seljuks, presided over a city that was still one of the great centers of Islamic learning and culture, but whose political authority extended little beyond the city itself. The Seljuk sultans, and later the Atabegs of Iraq, exercised effective power. The caliphs retained the loyalty of much of the Sunni Muslim world, and their legitimacy was invoked by the Seljuks, the Ayyubids, and the Mamluks of Egypt, none of whom claimed the caliphal title for themselves.

The Mongol invasion of the thirteenth century ended the Abbasid caliphate. The Mongol armies, led by Hulagu Khan, swept through Iran and Iraq and, in 1258, sacked Baghdad. The last Abbasid caliph, al-Musta’sim, was killed, and the great libraries and monuments of the city were destroyed. The Abbasid institution survived in a very limited form in Mamluk Cairo, where a line of caliphs in name only was maintained until the Ottoman conquest of Egypt in 1517.

The Abbasid Legacy

The Abbasid caliphate was, in many respects, the high point of the early medieval Islamic world. The political, institutional, and cultural achievements of the Abbasid period defined the classical civilization of Islam. The translation movement and the synthesis of Greek, Persian, Indian, and Syriac learning laid the foundations of the philosophy, science, and medicine of the medieval Islamic world and provided the bridge by which these traditions were eventually transmitted to the Latin West. The legal, theological, and mystical traditions of Islam took their mature form in the Abbasid period. The Arabic language, the language of the Qur’an and the caliphate, became the literary and scientific language of an enormous region.

The Abbasid legacy also includes the architectural and artistic traditions of the classical Islamic world. The Abbasid capital at Samarra, founded by the caliph al-Mu’tasim in 836, preserves the great mosque with its spiral minaret, the most ambitious example of Abbasid architecture. The caliphal palace at Baghdad, the round city of al-Mansur, and the various Abbasid palace cities of Iraq are attested in the sources, even if their remains are limited. The art of the Abbasid period includes the celebrated Samarra ceramics, the metalwork of the Iranian plateau, and the textiles of the great Abbasid factories. The story of the civilization that the Abbasids built is told in more detail in the Islamic Civilization and Learning.

Further reading

  • Hugh Kennedy, The Early Abbasid Caliphate (Croom Helm, 1981).
  • Michael Cooperson, Al-Ma’mun (Oneworld, 2005).
  • Toby Huff, The Rise of Early Modern Science: Islam, China, and the West, 3rd ed. (Cambridge University Press, 2017) for the comparative view.